Signal-wave transmission systems



June 19, 1956 Filed NOV. 22,l 1950 H. J. RIBLET SIGNAL-WAVE TRNSMISSIQN SYSTEMS E@ MMV 2 Sheet-Sheet 1 HEI/RY J. RIB E 7' 6) W June 19, 1956 H. J. RIBLr-:T

SIGNAL-WAVE TRANSMISSION SYSTEMS Filed NOV. 22, 1950 2 Sheets-Sheet 2 2,751,586? Patented June 19, 1956 SIGNAL-WAVE TRANSMISSION SYSTEMS Henry I. Riblet, Wellesley Hills', Mass., assigner to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application November 22, 1950, Serial No. 197,137

6 Claims. (.Cl. 343-16) This invention relates to electromagnetic-wave energy radiating and radiating-receiving devices, and more particularly to radiating and radiation-receiving structures comprising common radiating and radiation-receiving elements.

In transmit-receive devices such as, for example, radar systems, it is desirable to utilize a common antenna structure for both radiation and reception of the signals. By this structure, the radiating and receiving antenna may be aimed in a given direction, thus automatically positioni-ng the receiver in the direction necessary to receive echo signals for a given direction of the radiated signals.

ln order to obtain a greater degree of accuracy in ascertaining the directionv of reception of `a target signal, a process, commonly known as lobing, may be used. y In previous systems this lobing was carried out by transmitting successive pulses in slightly diierent directions in the general vicinity of the target and comparing the signal strength of the returning echoes from the various transmitted pulses.

This invention discloses a structure whereby simultaneous lobing in a plurality of different directions may be accomplished. Briey, this is achievedy by transmitting a single pulse from one radiation system in a particular direction and then receiving the reected signals simultaneously in a plurality of radiation-receiving systems, each system comprising said radiation system and being directiveV in slightly different directions from each other and from the direction of transmission of the radiated energy. Each set of receiving elements feeds a separate detecting device, and the outputs of the detecting devices are then compared to ascertain the precise direct-ion of the target.

In particular, this invention discloses a system for accurately producing a plurality of sets of radiation-receiving elements which are aligned with the desired directivities. Brieiiy, this is accomplished by using the radiating elements in conjunction with additional elements adjacent thereto, the composite element array for each group thus forming a directive-receiving antenna.

In order to connect the radiation-receiving elements to a signal-receiving channel, directional couplers may be used. In general, directional couplers are those couplersv which will couple energy from one channel into another channel such that a wave propagated in one direction in one channel will be coupled into the other channel by the couplers and be propagated in a predetermined direction therein.

In order to prevent energy from feeding directly from the radiating source into the receiving detectors, suitable switching means are provided between the radiating elements and the adjacent radiation-receiving elements, said switching. means substantially preventing energy from feeding from the radiating elements to the radiationreceiving elements during` radiation of a pulse of energy from said radiatingelements.

Other andV further objects and advantages of this invention will be apparentas-the description thereof progresses, reference being had to the accompanying drawings, wherein:

Fig. l illustrates a perspective" View of a radiating and radiation-receiving structure embodied in a system which utilizes this invention;

l Fig. 2 illustrates an end view of the radiating elements shown in Fig. 1;

Fig. 3 illustrates a partially broken away top plan view of the device shown in Fig. l; and

Fig. 4 illustrates a partial longitudinal, sectional View of the device shown in Figs. l, 2 and 3, taken along line 4 4 of Fig. 3.

Referring now to the drawings, there is shown a source of microwave energy 10 indicated, by way of example only, as a magnetron, said magnetron being connected to a section of wave guide 11 and adapted to propagate energy thereinto by means of a probe 12. One end of wave guide 11 is closed by means of an end plate 13, the distance of end plate 13 from probe 12 being governed by considerations of impedance match between the magnetron 10 and the wave guide 11 in accordance with wellknown principles. The other end of wave guide 11 is attached to a tapered wave guide section 14 which eiectively increases the dimensions of wave guide 11 in both directions until they are substantially double their original size.

Attached to the larger end of the tapered section are four wave guides 15, 16, 17 and 13, respectively, the crosssectional dimensions of which are substantially the same as those of wave guide 1v1. The other ends of wave guides 13, 16, 17 and 18 are attached to radiating elements, shown here, by way of example, as horns 19,` 20, 2i and 22, respectively. Horns 19, 20, 21 and 22 are aimed substantially in the same direction, and, therefore, when the magnetron 10 is energized, a pulse will be transmitted down wave guide 11 through tapered section 14, being divided substantially evenly between among the wave guides 15, 16, 17 and 18, and then being radiated by horns 19, 20, 21 and 22 in a relatively narrow or highly directional signal intensity pattern.

Reflected echoes from the radiated signal will then be received simultaneously by a plurality of systems of radiation-receiving elements in the following manner. Positioned above horn 19 is a horn 23. Positioned above horn 20 is a horn 24. Positioned on the opposite side of horn 20 from horn 19 is a horn 25. Positioned on the opposite side of horn 22 from horn 21 is a horn 26. Positioned below horn 22 is a horn 27. Positioned below horn 2 is a horn 2S. Positioned on the opposite side of horn 21 from horn 22 is a horn 29', and positioned on the opposite side of horn 19 from horn 20 is a horn 30. Horns 23 through 30 are attached to wave guides 31 through 38, respectively.

Wave guides 31, 32, 33 and 35 terminate in energyabsorbing material 39. Wave guide 33 makes a substantially right angular turn and passes across on top of wave guides 1S and 16, and below wave guides 31 and 32 such that the upper wall of wave guide 16 is adjacent the lower wall of wave guide 33, and the lower wall of wave guide 32 is adjacent the upper wall of wave guide 33.

Positioned in the adjacent walls of guides 32, 33 and 16 are directional coupling devices 40 and 41,A respectively. While it is to be clearly understood that any desired coupling may be used, the particular directional couplings shown here comprise pairs of crossed slots 40 and 41, respectively, points of intersection of the slots lying onV diagonals of the respective common surfaces of the adjacent Vwalls of the guides. The crossed-slot coupler 41 which connects wave guide 16 with wave guide 33 has a plurality of probes extending toward the point of intersection of the slots from the edges thereof, said probes having gaps therebetween which are small enough to break down when the pulse of energy is produced by the magnetron and propagated down the guide 114,. tapered section 14 and out through the horns. Therefore, substantially none of this energy will be coupled through the slot 41. However, received echo signals picked up by the horn will be coupled through the slot 41 into the guide 33 in the same direction as echo signals whlch are picked up by the horn 2S are fed into the guide 33. Similarly, echo signals picked up by the horn 24 will be coupled through crossed slot into the guide 33 1n the same direction as the echo signals propagated 1n the guides 33 from the horn 25. Thus, it may be seen that horns 24, 20 and 25 comprise a system of radiationreceiving elements all feeding energy into the common wave guide 33. At the end of wave guide 33, there 1s positioned a detector 42 of any desired type, shown here, by way of example, as a crystal diode. Energy from a local oscillator is fed into the guide 33 by a loop coupling through a coaxial cable 43, said energy beatlng with the incoming signals from the horns 20, 24 and 25 to produce an intermediate-frequency signal in a wellknown manner which is fed out through a line 44 to an intermediate-frequency amplifier.

Similarly, wave guides 18 and 35 couple energy lnto wave guide 34 through slots 45 and 46, respectively, slot 45 having breakdown probes therein. Signals are introduced into guide 34 from a. local oscillator by means of .Y

a loop coupling fed by a coaxial cable 47, and the resultant signal is detected by a detector 43 which feeds the detected signal to an intermediate-frequency amplifier through a line 49.

Similarly, guides 31 and 15 feed energy into guide 3S through slots and 51, respectively, and guides 17 and 36 feed energy into guide 37 through slots 52 and 53, respectively. Slots 51 and 52 have breakdown probes similar to slots 41 and 4S. Guides 37 and 38 terminate in detectors S4 and 55, respectively, which operate in l' conjunction with local-oscillator signals coupled into guides 37 and 38 through loops 56 and S7 fed by coaxial cables 58, 59, respectively, the outputs of detectors 54 and 55 being fed to intermediate-frequency stages through lines and 61, respectively. Thus, it may be seen that horns 19, 20, 21 and 22 act together to radiate a signal in a particular direction, but that horn 19 acts separately with horns 23 and 30 to receive echo signals in one direction. Horn 20 acts with horns 24 and 25 to receive signals with a slightly dilerent directivity. Horn 22 acts independently with horns 26 and 27 to receive signals in a still different directivity, and horn 21 acts with horns 28 and 29 to receive signals with an additional different directivity.

Furthermore, these four sets of horns receive signals simultaneously, and hence it is not necessary to send out f four diiferent signal pulses, as was the case of previous lobing systems, in order to obtain the desired signal ratios to ascertain the direction of a target echo.

Furthermore, it has been found that, by utilizing a portion of the radiating system used to radiate the pulses,

the eiective centers of the separate sets of receiving antennas may be placed closer together. As a result, the lobe patterns of the sets of receiving antennas overlap up to substantially greater distances from the antenna than would be the case if separate receiving antenna systems were used. As a result, a lobing system is produced which is effective both at long ranges and at close ranges to ascertain the direction of the received echo signal with high precision.

This completes the description of the particular species of the invention described herein. However, many modications thereof will be apparent to persons skilled in the art without departing from the spirit and scope of this invention. For example, the same principle of utilizing portions of the signal-radiating system in conjunction with F additional signal-receiving elements to improve the overall lobe pattern may be applied to other lobing systems than the one described herein. For example, it could be applied to a lobing system of the so-called sequential type which is now in general use today.

Furthermore, the particular configuration and waveguide structures, shown here, are by way of example only, and any desired wave guide structure or wavetransmission structure could be used. Therefore, it is desired that this invention be not limited to the particular details of the embodiment illustrated herein, except as defined by the appended claims.

What is claimed is:

1. An echo ranging system comprising means for radiating signals, and a directive-receiving channel fed by radiation-receiving means differing in radiation directivity from said radiating means, said radiation receiving means including said radiating means, said radiation-receiving means being connected to said channel through directivecoupling means.

2. A signal-wave transmission system comprising means for dircctively radiating signals comprising a radiating horn, and a receiving channel fed by radiation-receiving means differing in radiation directivity from said radiating means, said radiation receiving means comprising said horn and an additional horn adjacent said first-mentioned horn, and a directional coupler connecting said first-metioned horn with said receiving channel.

3. An acho ranging system comprising a source of signals, a signal-radiating channel fed by said source and feeding means for directively radiating said signals, a receiving channel fed by radiation-receiving means differing in radiation directivity from said radiating means, said radiation-receiving means including said means for directively radiating said signals, and switching means disconnecting said signal-radiating channel from said signalreceiving channel in response to signals from said source.

4. A signal-wave transmission system comprising a source of signals, a signal-guiding channel fed by said source and feeding means for directively radiating said signals, a receiving channel fed by radiation-receiving means including said radiating means but dilering in radiation directivity from said radiating means, and Switching means connecting said signal-guiding channel with said signal-receiving channel, said switching means being operative in response to signals from said source to disconnect said signal-receiving channel from said signal-guiding channel in response to signals from said source.

5. A signal-wave transmission system comprising a source of signals, a signal-guiding channel fed by said source and feeding means for directively radiating said signals, a receiving channel fed by radiation-receiving means including said radiating means but differing in radiation directivity from said radiating means, and switching means connecting said signal-guiding channel with said signal-receiving channel, said switching means comprising a directional coupler.

6. An echo ranging system comprising a source of signals, a signal-guiding channel fed by said source and feeding means for directively radiating said signals, a receiving channel fed by radiation-receiving means including said radiating means but differing in radiation directivity from said radiating means, and switching means connecting said signal-guiding channel with said signalreceiving channel, said switching means comprising a crossed-slot directional coupler.

References Cited in the file of this patent UNITED STATES PATENTS 2,473,274 Bradley June 14, 1949 2,480,829 Barrow et al. Sept. 6, 1949 2,514,351 Smith luly 4, 1950 2,523,398 Southworth Sept. 26, 1950 2,567,197 Fox Sept. 11, 1951 2,587,590 Brewer Mar. 4, 1952 FOREIGN PATENTS 575,432 Great Britain Feb. 18, 1946 627,690 Great Britain Aug. 15, 1949 

